If you turn the volume knob while the NAV System is talking it adjusts the NAV System volume and not the radio volume as expected. My guess is that you thought you were turning down the radio to hear the NAV and actually turned down the NAV.
You will note that the color of the volume bar on the screen changes for radio or NAV when adjusting.
You will note that the color of the volume bar on the screen changes for radio or NAV when adjusting.
